Format C with clang-format and Fortran with fprettify

1. Copy .clang-format from libcdi.
2. Add a CI job that checks the formatting and uploads a patch if the formatting has to be fixed.
3. Apply the formatting.
4. Add .git-blame-ignore-revs, which can be used as an extra argument for git blame to ignore the formatting commit (e.g. git blame --ignore-revs-file .git-blame-ignore-revs src/mtime_eventHandling.c).

Luis, check whether you are fine with how the code looks after the formatting.